The modulatory sites on the GABAA receptor complex, such as for example the benzodiazepine binding site, are the targets for anxiolytic drugs, such as the classical anxiolytic benzodiazepines. However, they are associated with a number of undesirable features.
Multiple isoforms of the GABAA receptor exist; each receptor is a pentameric complex comprising subunits drawn from α1-6, β1-3, γ1-3, δ, ε, and θ subunit isoforms. The classical anxiolytic benzodiazepines show no subtype selectivity. It has been suggested that one of the key elements in the disadvantages of the classical benzodiazepanes (such as sedation, dependency, and cognitive impairment) is related to the α1 subunit of the GABAA receptors. Thus compounds with selectivity for the α2 and/or α3 subunits over the α1 subunit are expected to have an improved side effect profile.
Thus, there is still a strong need for compounds with an optimised pharmacological profile. Furthermore, there is a strong need to find effective compounds without unwanted side effects associated with older compounds.